Electric switch



J. G. JACKSON 1,988,687

ELECTRIC SWITCH Jan. 22, 1935.

Filed 0ct. 6, 1930 ATTORN EY'S Patented Jan. 22, 1935 ELECTRIC SWITCHJohn G. Jackson, Detroit, Mich., assignor to Square D Company, Detroit,Mich., a corporation of Michigan Application October 6,1930, Serial No.486,856

5 Claims.

This invention relates generally to electric switches and refers moreparticularly to knife or jaw switches.

One of the essential objects of the invention 5 is to provide a switchof this type in which the or arcing.

Another object is to provide a switch in which the ribs constitute thesecond and final stage of contact and exert a higher pressure againstopposite sides of the blade than that exerted by the walls of thecup-shaped recess. I

Another object is to provide a switch in which the jaw plates areprovided with spring backers that lie flatagainst the jaw plates andcause the ribs aforesaid to grip firmly and positively the knife bladeorbar so that a better contact between the parts is obtained.

Another object is to simplify, improve generally and render moreefiicient switch structures of the type described.

'Other objects, advantages, and novel details of construction of thisinvention will be made more apparent as this description proceeds,especially when considered in connection with the accompanying drawingwherein:

Figure 1 is an edge elevation of a switch embodying my invention andshowing the knife blade about to enter the jaw;

Figure 2 is a. view similar to Figure 1 but showing the parts after theknife blade is in engagement with the jaw;

Figure 3 is a side elevation of the structure illustrated in Figure 1,omitting the knife blade.

Referring now to the drawing, A is a terminal bar of good conductingmaterial such as copper; B is a jaw embodying my invention extendingupwardly from. the bar A; and C is a movable knife blade or barengageable with the jaw B to close an electric circuit. As shown, theterminal bar A is substantially L-shape and has a said plates.

Preferably the plates 2 and 3 are secured at their lower ends toopposite sides of the upright portion 6 of the terminal bar A and areprovided at their upper ends with opposed inwardly projectingtransversely extending outwardly opening substantially channel shape em-5 bossed portions or ribs '7 and 8 respectively and opposed outwardlyextending curved end portions 9 and 10 respectively. As shown in Figure1, the ribs 7 and 8, curved end portions 9 and 10 and intermediateparallel portions 11 and 12 re- 10 spectively of the plates form acup-shaped recess for the reception of the knife blades C.- The springbackers 4 and 5 are preferably plates of spring metal that are fiatagainst the outer faces of the parallel plates 2 and 3 and extend from15 the lower ends thereof to points below but adjacent to the ribs 7 and8. Preferably rivets 13 extend through the upstanding portion 6 of theterminal bar at spaced points thereof and constitute a common securingmeans for the plates 2 and 3 and spring backers 4 and 5.

In use when the knife blade C is inserted between .the plates 2 and 3the curved end portions 9 and 10 of said plates will guide the knifeblade inwardly between the plates. The blade C will first contact withopposite sides of the cup shaped recess and will then be engaged by theribs '7 and 8. The spring backers 4 and 5 resist the separation of theribs 7 and 8, hence when the ribs 7 and 8 are separated by the knifeblade C, the backers 4 and 5 are under tension and cause the said ribsto press against and firmly grip the knife blade. In fact, theconstruction and arrangement of the ribs is such that an extremely fineline contact with opposite sides of the knife blade C is obtained. InFigure 1 it will be noted that the knife blade C is in a plane parallelto the planes in which the plates 2 and 3 are located, however, theconstruction and arrangement of the parts is such that if the blade Cshould not be parallel but should be inclined somewhat relative to theplates when inserted therebetween, the ribs 7 and 8 will still grip andform line contact with said blade. Moreover, such line contact will beobtained regardless of how far the blade is inserted between the ribs 7and 8. Thus a better and more eflicient contact is made for theconveyance of electric current.

Thus from the foregoing it will be readily apparent that I have provideda two stage contact switch wherein the pressure exerted by the sidewalls of the recess is relatively light while the final contact of theribswith the blade is comparatively heavy. Similar1y.' when the blade iswithdrawn from the ribs into the cup-shaped recess the contact pressureis relieved and when the blade is withdrawn i'rom the recess the circuitis broken.

While I have shown and described a switch comprising separately formedplates 2 and 3, it is apparent such plates may be integral in the .formof a U or may be integral with the upright portion 6 of the terminal barA.

What I claim as my invention is:

1. An electric contact anchored at one end and free at the other, saidcontact being provided between said ends with longitudinally spacedmeans for successive engagement with a cooperating contact, the meansinitially engageable by said cooperating contact being capable ofcarrying the full load until the second means is engaged and comprisingsubstantially parallel portions formed to subject the cooperatingcontact to a preliminary pressure and hold the same, the meanssubsequently engageable by saidcooperating contact comprising opposedportions disposed closer together and formed to subject said cooperatingcontact to a greater pressure and hold the same.

2. An electric contact anchored at one end and free at the other, saidcontact being provided at its free end with flaring guide means for acooperating contact and provided between said ends with longitudinallyspaced means ior successive engagement with such cooperating contact,the means initially engageable by said cooperating contact beingadjacent the flaring guide means and comprising substantially parallelportions formed to subject the cooperating contact to a preliminarypressure and hold the same, and the means subsequently engageable bysaid cooperating contact being nearer to the anchored end aforesaid andcomprising opposed portions disposed closer together and formed tosubject such cooperating contact to a greater pressure and hold thesame.

3. An electric contact provided with longitudinally spaced means forsuccessive engagement with a cooperating contact, the means initiallyengageable by said cooperating contact comprising substantially parallelportions constructed and arranged to subject the cooperating contact toa preliminary pressure and hold the same, and the means subsequentlyengageable by said cooperating contact comprising opposed portionsintegral with the parallel portions but constructed and arranged tosubject the cooperating contact to a greater pressure and hold the same.

4. An electric contact anchored at one end and having flaring guideportions at its other end, said contact being provided between saidanchored end and flaring guide portions with longitudinally spaced meansfor successive engagement with a cooperating contact, the meansinitially engageable by said cooperating contact comprising opposedportions constructed and arranged to subject the cooperating contact toa preliminary pressure and hold the same, and the means subsequentlyengageable by the cooperating contactcomprising opposed portions thatare closer together-than the opposed portions just mentioned and areformed to subject the cooperating contact to a greater pressure and holdthe same.

5. An electric contact having substantially parallel members anchored atone end and provided at the other end with flaring guide portions for acooperating contact, said members being provided intermediate theiranchored ends and flaring guide portions with longitudinally spacedmeans for successive engagement by such cooperating contact, the meansinitially engageable by said cooperating contact comprisingsubstantially parallel portions offset inward ly relative to saidmembers, said parallel por-.

